1. Field of the Invention
This invention relates to a handy image scanner used for inputting script images to a personal computer or a word processor.
2. Related Art
In order to efficiently illuminate script images, a light gathering lens must be placed between a light source and a script. A handy image scanner for imaging scripts must additionally have a transparent cover on the bottom to prevent dust from entering the apparatus. Consequently, the ability to provide an image scanner of small size is limited by the necessity of providing a separate light gathering lens and transparent cover. Also, installation is difficult because the optical axis of the light gathering lens and the transparent cover must be adjusted to allow a light from the light source to be properly illuminated onto the script. Accordingly, the complicated assembly leads to a high production cost.
FIG. 2 shows a cross-sectional view of the structure of an image scanner according to the above-described known scanner. The image scanner is provided in a casing 1. A reading window 2 and a transparent cover 3 are provided along the front part of the bottom portion of the casing 1 and constitute the portion of the apparatus through which a script G will be imaged. The script G is illuminated by light generated from a fluorescent light source 4 and directed through a light gathering lens (not shown) to the transparent cover 3. Since this light passes through the transparent cover 3 at an oblique angle, some incident rays are upwardly reflected (shown by arrows). The light passing through the transparent cover 3 and the reading window 2 illuminates the script G and then is reflected back into the apparatus, through another part of the transparent cover 3, in the direction of a reflecting mirror 5. However, some of this reflected light is also lost due to downwardly scattering incident reflected rays as the light again passes through the transparent cover 3 at an oblique angle. The light that does reach the reflecting mirror 5 is reflected to another reflecting mirror 6 and directed to a converging lens 7. From the converging lens 7, the light, containing script G image information, is focused onto a charge coupled device (CCD) 8, thereby generating an image data signal.
Another problem with the known scanner lies in the fact that a percentage of the light emitted from the light source 4 is lost due to both the upward and downward incident rays reflected from the top and bottom of the transparent cover 3 respectively. To compensate for decreased script G image illuminance due to this lost light, the light source 4 must increase illumination and therefore use more electrical power. Another problem stems from the upwardly reflected incident rays. These rays are directed in the general direction of the reflecting mirror 5 and if reflected thereby would ultimately reach the CCD 8 and detract from the quality of the image produced by the image scanner. Therefore, the image scanner in FIG. 2 must also include an interruption plate (not shown) located between the transparent cover 3 and the reflecting mirror 5, wherein the interruption plate blocks incident rays while allowing the reflection from the script G to pass.